In order to produce color images, such as photograph and video images, demosaicing and image warping are often performed in succession on images resulting in rectified color images.
A demosaicing algorithm is a digital image process that is used to reconstruct a full color image from incomplete color output from an image sensor overlaid with a color filter array in order to render the image into a viewable format. As the raw color image includes an intensity of only one color of the three filter colors (red, blue, and green) per pixel, demosaicing is used to determine intensities of the other two colors for each pixel. Many algorithms exist for demosaicing a color image. These algorithms vary in complexity and may result in a tripling of the data involved.
Image warping is the process of smoothly displacing the pixels in an image. In a warped image, the value at each pixel is usually computed from values sampled in the original image. Since the location in the raw image does not necessarily have integer coordinates, some interpolation is typically needed. Warping is used, for example, to correct for distortions present in an image. An image produced by an optical system is subject to various forms of geometric distortion. The distortion is often significant enough that it is desirable to warp the image into a more usable form. For example, objects in the center of an image obtained using a wide-angle or fish-eye lens will appear enlarged compared to objects at the edges. This is called barrel distortion. Warping the image may correct for the barrel distortion, resulting in a proportionally correct image that would appear to have been produced by a perspective camera. Warping can also be used to correct other types of distortions, or even to purposely cause distortions.
Both demosaicing and warping introduce some image defects, or artifacts, because they typically each involve interpolation. Performing demosaicing and warping individually in succession compounds this issue. In addition to the processing time needed to perform the two operations, demosaicing and warping in succession requires computer memory to store an intermediate image and also requires interpolations being performed twice.
In the drawings, the leftmost digit(s) of a reference number may identify the drawing in which the reference number first appears.